If a detectorist doesn't understand how their
detector fully works, potentially they could be missing gold nuggets. Metal
detectors work on the principle of conductivity. All metal objects, whether
ferrous or non-ferrous are conductive. That is, heat and electricity can flow
through them.

A metal detector creates an Electro-Magnetic
Field which penetrates into the ground. When this field comes across a
conductive metal object, the search coil senses a charge in the field, and thus,
detects the objects buried below. A signal is then sent to the control box,
which drives a loudspeaker, meter or headphones and emits a noise, alerting the
operator of a potential object.

Metal detectors react to the surfaced area of an
object, not its mass. The larger the surface area, the deeper you will be able
to detect an object. For example, a coin lying flat will be detected at a
greater depth than the same coin standing on it's edge. In addition to metals,
a detector may react to iron ores, magnetic non-conductive minerals and beach
salts. These non-metallic substances are known as mineralized ground and cause
a detector to produce a false signal or ground noise.

To eliminate this ground noise, the detector has
a ground balance function to compensate for the levels substances in the ground
being searched.

"Detector Technology"

What is Automatic Ground Tracking (AGT)?

AGT refers to the ability of the detector to track the changes
in ground mineralization and automatically adjust the ground balance to suit.
This ensures perfect ground balance and full detection depth and eliminates the
need for the operator to stop and manually adjust the detector as the ground
conditions change. The Minelab SD2100 does not have auto ground
tracking.

What is Very Low Frequency (VLF) Technology?

Conventional VLF detectors transmit a continuous
magnetic field into the ground on one set frequency. This VLF technology as the
name implies, operates at low frequencies. The conventional range is from 3 kHz
to 50 kHz.

Minelab now produces detectors which operate at
slightly higher than 50 kHz and lower than 3 kHz frequencies to gain greater
depth and sensitivity. Some models operate in a number of frequencies which
allows you to choose the most effective range for the particular type of
detecting. The Minelab GT15000, 16000, American Gold Striker, XT17000,
XT18000 & latest Eureka Gold all use this VLF technology.

What is Broad Band Spectrum (BBS) Technology?

Unlike other metal detectors which operate on one
or two frequencies, BBS technology transmits multiple separate frequencies over
a range of 1.5 kHz to 25.5 kHz. All multiple frequencies are transmitted at the
same time, spread over a wide spectrum. BBS technology means you have more
depth, greater and more accurate discrimination. The Minelab Sovereign
series & Excalibur use this technology.

What is Full Band Spectrum (FBS)?

FBS technology is a further development of
Minelab's BBS Multi Frequency Technology. This Technology is unique to
Minelab, providing greater depth and improved target identification in most soil
conditions. FBS refers to the use of 28 frequencies operating
simultaneously over a range from 1.5kHz to 100kHz. FBS Technology means
that a wider range of targets can be located at greater depths. The
Minelab Explorer II & the latest Minelab Quattro use this technology.

What is Multi-Period Sensing (MPS) Technology?

It transmits a stream of alternating short and
long pulses of magnetic field into the ground. These pulses cause metal objects
in the ground to produce a changed magnetic field of their own. MPS technology
is able to locate metal targets up to four times the depth of conventional
detectors. MPS also means that very small targets may be found in the most
difficult ground and you will dig less ground signals. The Minelab SD2100,
SD2100v2, SD2200d, SD2200v2 & the GP Extreme detectors all use this type of
technology.

What is Dual Voltage Technology (DVT)?

DVT refers to changes in the voltage used to
create the electro-magnetic field transmitted from the coil into the ground.
By using two different voltages (DVT) the possibilities of magnetic saturation
of the ground is lessened. Thus, detectors using DVT have an increased
ability to balance out ground mineralization providing increased depth
and greater sensitivity compared with other detectors. The latest
Minelab GP3000 Metal Detector uses this technology. What to see more on
the Minelab GP3000? "Click Here!"

What are Operating Frequencies?

Frequencies in a metal detector are referred to
in kHz (kilo hertz) which is the number of times a signal is transmitted into
the ground as received back per second. The lower the detector's frequency, the
deeper it will penetrate. However, its sensitivity to smaller targets may be
reduced. On the other hand, the higher the detector's frequency, the higher its
sensitivity to even the smallest targets, but it may not penetrate as deeply.